Etching mechanism



Oct. 22, 1968 5H, M1TCHELL ET AL 3,406,697

ETCHING' MECHAISM .filed March 4, i966 2 Sheets-Shes Get. 22, 1968 E, H, MV1-@HELL ET AL. 3,406,697

ETCHING MECHANI SM United States Patent 3,406,697 ETCHING MECHANISM Ernest H. Mitchell, Sunland, and Alvin E. Mueller, Downey, Calif., assignors to Western Technology, Inc., Santa Ana, Calif., a corporation of California Filed Mar. 4, 1966, Ser. No. 531,716 2 Claims. (Cl. 134-148) ABSTRACT F THE DISCLOSURE A chemical etching machine is described herein, in which a vertical rotary member is supported between a pair of guides, the rotary member being driven by an eccentric drive which is coupled to its periphery. The workpiece is attached to the rotary member, and etchant sprays are directed against it. Then, when the rotary member is driven, it and the workpiece are rotated and reciprocated with respect to the etchant sprays,

The present invention relates to an improved chemical etching machine which is constructed specifically for performing etching operations on an experimental prototype, or on a limited production basis, but which has general utility. The invention is particularly concerned with a simple and inexpensive chemical etching machine in which the workpiece is supported on a vertical, rotary, planetary member.

Chemical etching machines are described and claimed in copending application Ser. No. 396,022 tiled Sept. 14, 1964 which has now issued as Patent 3,266,502. In the use of such a machine, the workpiece is initially selectively masked, for example, by a film of photo-resist material. The unmasked areas of the workpiece are then exposed to the action of the etchant sprays in the machine.

In the etching machine to be described, the workpiece is supported in a vertical plane on a vertical, rotary, planetary member, as mentioned above. The workpiece is rotated in the vertical plane, and it is simultaneously moved up and down, as the etchant spray is directed against it. The member is removed from the etching chamber of the mechanism at the termination of the etching process, and it is then placed in a rinse chamber to complete the process.

The cabinet of the machine is preferably constructed of heat welded, polyvinyl chloride panels, or of other appropriate material which is immune to attack by the etchant. The internal components of the machine which are likely to come in contact with the etchant are composed, for example, of titanium, or of other suitable material for maximum reliability and long life.

The machine of the invention has the feature of being compact and fully self-contained, so as to be suitable for use in environments Where cleanliness is essential. Moreover, the machine can be operated Without the need for special protective clothing on the part of the operator.

The embodiment to be described includes a reservoir for the etchant, and a combined motor/centrifugal pump unit is set down into the reservoir to pump the etchant to the spray nozzles so as to maintain a smooth flow of the etchant to the workpiece` The reservoir may contain, for example, from two to twenty-five gallons of the etchant solution.

A separate motor is provided to drive the planetary mechanism in the embodiment to be described. The planetary mechanism includes a disc-shaped vertical, rotary, planetary support member which is mounted for rotation and for up-down linear movement in a grooved track. An eccentric drive is provided from the motor to the periphery of the disc, so that the disc may be rotated in the track and, at the same time, be moved up and down.

3,406,697 Patented Oct. 22, 1968 "ice In this manner, the workpiece supported on the disc is assured to receive the etchant spray uniformly over its entire surface. The disc may support one or more Workpieces on either or on both its faces. Moreover, the disc may have an annular configuration, and it may support the workpiece in an opening at its center. Then, both sides of the workpiece may be sprayed simultaneously in the etching chamber.

The embodiment of the invention to be described incorporates a ooded rinse chamber, and a circulating rinsing bath on the top of the unit. The construction is such that the disc and supported workpiece are placed into the etching chamber from the top of the housing, and they can be removed from the etching chamber when the etching process is completed and inserted down into the rinse chamber.

During the transfer operation, any etchant which might have dropped from the disc and supported workpiece onto the top of the cover is washed away by circulating water.

The circulating water bath at the top of the machine may conveniently drain into the rinse chamber. This bath, as mentioned above, disposes of any etchant which might have dripped from the workpiece, disc, or xture, during the transfer of the assembly from the etching chamber to the rinse chamber.

The features of the invention which are believed to be new are set forth with particularity in the claims. The invention itself, however, together with its further objects and advantages, may best be understood by reference to the accompanying drawings, in which:

FIGURE 1 is a perspective view of an etching machine which may be constructed to incorporate the concepts of the present invention;

FIGURE 2 is a perspective view of the aforesaid disc which supports the workpiece in the interior of the machine of FIGURE 1;

FIGURE 2a is an enlarged perspective view of an adjustable support bracket which may, together with a like bracket, be mounted on the disc of FIGURE 2 to support the workpiece;

FIGURE 3 is a perspective view, on a reduced scale, of the disc of FIGURE 2 supported within the machine of FIGURE 1;

FIGURE 4 is a side sectional view of the machine, showing the internal components which go to make up the machine;

FIGURE 5 is a fragmentary side section view showing, `on an enlarged scale, the manner in which the drive motor shaft for the vertical, rotary, planetary mechanism is sealed in the wall of the etching chamber; and

FIGURE 6 is a perspective view, showing a section of the top cover of the machine, and the manner in which a water rinse bath is providede over the top of the mechanism.

As shown particularly in FIGURE 1, the illustrated embodiment of the present invention includes an outer housing, or cabinet, 10. The housing, or cabinet, 10 may be composed of any suitable material which is capable of withstanding the action of the etchant used in the machine. For example, polyvinyl chloride sheets have been found to be ideal for this purpose.

As shown in FIGURES 1 and 4, the machine includes an etching chamber 12 and a rinse chamber 14. A window 16 composed, `for example, of clear polyvinyl chloride may be provided so that the action within the etching chamber 12 may be observed.

A cover 18 is provided for the cabinet 10, and this cover has a rst opening 20 disposed over the etching chamber 12, and it has a second opening 22 disposed over the rinse chamber 14. These openings are in the form of transverse slots which extend across the cover 18.

A pair of vertical tracks 26, 28 (FIGURES 3 and 4) are mounted on the sides of the etching chamber 12 to be in spaced and parallel relationship. These tracks receive a disc-like member 30. The disc may be inserted into the etching chamber by dropping it down between the tracks as shown in FIGURE 3. The disc is driven as will be described so that it is rotated and is simultaneously moved up and down in the tracks.

The workpiece to be treated in the mechanism is mounted on the disc 30 in any suitable manner. For example, the disc-like member may have an lannular configuration with an opening 31 to receive the workpiece. The workpiece may be supported in the opening 31 by means, for example, of adjustable brackets 33. As shown in FIGURE 2a, the brackets 33 have notches at each end, and are provided with screws which serve to clamp the brackets to the disc 30 at selected positions across the opening 31. This latter configuration permits both sides of the workpiece to be treated simultaneously.

The opening 20 is provided with a hinged cover 24, as shown in FIGURES l, 4 and 6. In the operation of the machine, the cover 24 is opened and the disc 30 with its attached workpiece, or workpieces, are inserted first into the opening 20 in the etching chamber, and down between the tracks 26 and 28 to the position shown in FIGURE 3. At the end of the etching operation, the disc and workpiece are removed from the etching chamber 12, and are inserted into the rinse chamber 14 through the opening 22.

A main power switch 34 and associated pilot light 36 are mounted on the cabinet 10, and a timer control 38 is also mounted on the cabinet (FIGURE l). Appropriate heating and cooling coils may be positioned in the etching chamber so as to maintain a constant temperature of the etchant. This temperature may be controlled, for example, by an appropriate thermostat control 40.

In the operation of the mechanism, therefore, the disc 30 is first placed in the etching chamber 12 in the manner described above. An appropriate etching iiuid to be used in the machine may be ferrie chloride, ammonium persulphase, or chromic-sulfuric. The timer control 38 is set, the machine is turned on. Then, after a predetermined time, and after the workpiece has been processed, the machine shuts itself olf. The disc 30 is then removed from the etching chamber, and it is placed into the rinse chamber, so that the processed workpiece may be rinsed.

The aforesaid electrical controls may all be commercially available units. For example, the heater coils may be one kilo-watt electrical coils encased in titanium or quartz sheaths. .The power -for the unit may be supplied from the usual 11S-volt, alternating current mains, and the current drawn by the mechanism may be of the order of 17 amps. The timer 38 may be of the automatic reset type, and it may be capable of establishing etching times of from zero to fifteen minutes.

As shown in FIGURE 4, a drive motor for the disc 30 is provided in a separate chamber 52. The motor 50 includes a drive shaft 54 which extends through a wall 56 into the etching chamber 12. The etchant is housed in a reservoir 58 at the bottom of the etching chamber. The normal level of the etchant is below the level of the shaft 54.

A drive wheel 60 is eccentrically mounted on the shaft 54. This drive wheel is in position so that when the disc 30 is lowered down between the tracks 26, 28 into the etching chamber 12, the periphery of the disc 30 will engage the periphery of the eccentric wheel 60. Both these peripheries may be chamfered so as to assure a good drive relationship between the wheel 60 and the disc 30.

It will be appreciated that as the motor 50 drives the eccentric wheel 60, the disc 30 is caused to rotate in the tracks 26 and 28, and also to move up and down in the tracks. The motor 50 may, for example, be a 30 r.p.m. gear motor.

A pump 70 is positioned down in the reservoir S8 below the normal etchant level. This pump may be part 4 of an integral pump-motor u nit 72, the motor being positioned in a further chamber 74. The pump 70 has an outlet coupled by pipes 76 to a pair of nozzles 78 and 80 in the etching chamber. These nozzles are mounted in the etching chamber on opposite sides of the disc 30, and are fixed in position.

As the vertical disc 30 is rotated and moved reciprocally, all areas of the supported workpiece are caused to be uniformly sprayed by the etchant issuing from the nozzles 78 and 80. The motor/pump assembly 72 may be any appropriate commercially available unit.

The outer assembly of the pump 70 is mounted directly to the bottom of the machine, so that all plumbing may be permanent. The inner part of the pump may be lifted out with the motor 72 for servicing, without any need to disconnect the pipes 76, or other components. Also, the electric leads to the motor portion of the integral unit 72 may be provided with plugs, so that the entire motor and inner components of the pump may easily be removed as a unit.

The details of the rinse chamber 14 are shown in FIGURE 4. As illustrated, the rinse chamber is in the form of a tank which is illed with water. When the disc 30 and its supported workpiece are inserted into the rinse chamber, they -are merely submerged under the level of the water in the rinse chamber.

Water is introduced into the rinse chamber from the usual water mains through an inlet 100, and it is discharged to the usual drain through -an outlet 102. A stand pipe 104 is provided in the rinse chamber 14 to maintain a desired level of water in the chamber. The stand pipe is removable to permit the rinse chamber to be drained. -It will be appreciated that the Water is always circulating through the rinse chamber.

The manner in which the shaft of the motor 50 is sealed to the wall 56 is shown in FIGURE 5. The shaft 54 is compared to titanium, or other yappropriate material. The eccentric wheel 60 is mounted on the end of the shaft 54 is composed of titanium, or other appropriate material. 60a of the wheel 60 is sealed against the wall 56 by means, .for example, of an O-ring 121.

An annular member 122 is supported on the shaft 54 on the opposite side of the wall 56. The member 122 is spring biased towards the wall by means, of a spring 123. An O-ring 124 provides a seal between the member 122 and the Wall 56.

The cover 18 is shown in further detail in FIGURE 6. The cover may be formed, for example, by a vacuum forming process, and it may be composed of clear polyvinyl chloride.

Also, a plurality of nozzles 150 are provided in a channel 151 which extends along a side of lthe cover; and water or other suitable rinsing solution is forced through the nozzles 150 to wash the -top of the cover. As shown in FIGURE l, the water inlet pipe in the rinse chamber has a branch 100a which extends down into the rinse chamber to supply water thereto. The inlet pipe 100 also includes a branch 100b which extends up into the channel 151 to supply water to the channel.

The cover is configured so that ridges are formed to provide a shallow tank, or bath, for the rinsing solution. The rinsing solution is permited to drain down through the opening 22 into the etching chamber. This serves to remove any etchant from the top cover 18, which might drip olf the lfixture 24, disc 30 or supported workpiece, as the assembly is being transferred from the etching chamber to the rinse chamber.

The invention provides, therefore, an improved and relatively simple etching mechanism which finds particular utility in laboratories and for limited production runs.

The mechanism of the invention is particularly advantageous in that it is simple to operate and is completely self-contained. This means that the equipment can be used without contaminating the surrounding evironment,

and without the need for the operator to use special protective clothing.

While a particular embodiment has been shown and described, modifications may be made. It is intended in the following claims to cover the modifications which come within the scope of the invention.

What is claimed is:

1. In an etching machine in which an etchant is sprayed against a workpiece, the combination of: a housing defining an etching chamber and having a top with an opening therein, said etching chamber including a lower portion for holding an etchant solution; a disc-shaped support member for the workpiece supported in said etching chamber for rotation of said workpiece in a vertical plane, said disc-shaped support member being removable through said opening in the top of said housing; spray nozzle means mounted in said etching chamber for directing an etchant spray at said workpiece; pump means coupled to said lower portion of said etching chamber and to said spray nozzle means for pumping said etchant solution from said lower portion of said chamber to said spray nozzle means; a pair of spaced and parallel grooved track members mounted in said etching chamber for supporting said discshaped support member therebetween at the periphery thereof with said support member being disposed in the aforesaid vertical plane for rotational movement and reciprocal rectilinear vertical movement of said workpiece with respect to said spray noule means; and drive means in said etching chamber for applying rotational movement to said workpiece and causing rotational and reciprocal rectilinear movement thereof relative to said spray nozzle means, said drive means consisting of a shaft and a drive wheel mounted on said shaft in position to engage the peripheral surface of said disc-shaped support member to apply the aforesaid rotational movement to said workpiece and to cause the aforesaid rotational and reciprocal rectilinear movement thereof relative to said spray nozzle means.

2. The combination defined in claim 1, in which said drive wheel is eccentrically mounted on said drive shaft in position to engage the peripheral surface of said discshaped support member.

References Cited UNITED STATES PATENTS 3,088,391 5/1963 Sigler 134-153 XR 3,135,272 6/1964 Brollo 134-199 XR 3,327,721 6/1967 Carlson 134--153 XR FOREIGN PATENTS 526,057 6/ 1931 Germany. 552,025 1/1956 Italy.

OTHER REFERENCES Ofca et al.: Etching Holes in Metal Masks, IBM Technical Disclosure Bulletin, vol. 5, No. 4, September 1962, pp. 6 and 7.

ROBERT L. BLEUTGE, Primary Examiner. 

